There is no SIP client for voip comunication anymore in gentoo.
Ekiga, Linphone, yate (GUI) are no longer available.
Other clients such as Jitsi are more difficult to install.
For several weeks I have been testing baresip (command line SIP) and it works very well. Call quality is superior to anything I have used in the past.
I would recommend latest not the 0.6.4 version which had some bugs.